Polymer Polyethylene Research Articles

Detection of microplastics in Litopenaeus vannamei (Penaeidae) and Macrobrachium rosenbergii (Palaemonidae) in cultured pond.

BackgroundThe presence of plastic particles in freshwater species is becoming a global concern owing to the potential impact on food security and human health. In this study, we investigated the presence microplastics (MPs) in two economically important freshwater species: the giant freshwater prawn (Macrobrachium rosenbergii) and the white leg shrimp (Litopenaeus vannamei) cultured in a polyculture pond in the central part of Thailand.MethodsThe gastrointestinal tract (GT) of 300 giant freshwater prawn (160 female and 140 male) and 150 white leg shrimp specimens were investigated for the presence of MPs.ResultsFrom the pooled samples, a total of 1,166 MP items were identified. Specifically, the GTs of female and male freshwater prawns and white leg shrimps contained an average of 33.31 ± 19.42, 33.43 ± 19.07, and 11.00 ± 4.60 MP items per individual, respectively. Further, their mean MP contents per g of gut material were 32.66 ± 5.10, 32.14 ± 4.85, and 10.28 ± 1.19 MP items, respectively. In the GT of these species, MPs with sizes in the range 500–1000 µm, were predominant, and white/transparent MPs were most prevalent (63.67%). Furthermore, regarding the morphotypes of the MPs, fibers, fragments, films, and spheres were frequently observed, with fibers shows predominance. Specifically, the proportions of fibers in the GTs of female Macrobrachium rosenbergii, male Macrobrachium rosenbergii, and Litopenaeus vannamei were 83.3, 79.91, and 46.06%, respectively. Four MP polymer types, polyethylene, polycaprolactone, polyvinyl alcohol, and acrylonitrile butadiene styrene, were also identified via FTIR spectroscopy, which further confirmed the presence of MPs in the GT of the freshwater-cultured species.DiscussionOur findings indicated that consuming shrimps and prawns without first removing the MPs from their GTs is one of the mean by which humans get exposed to MPs. Thus, MPs in freshwater species can be passed down the food chain to humans.

Stealth Liposomes (PEGylated) Containing an Anticancer Drug Camptothecin: In Vitro Characterization and In Vivo Pharmacokinetic and Tissue Distribution Study.

Numerous attempts to overcome the poor water solubility of cam ptothecin (CPT) by various nano drug delivery systems are described in various sources in the literature. However, the results of these approaches may be hampered by the incomplete separation of free CPT from the formulations, and this issue has not been investigated in detail. This study aimed to promote the solubility and continuous delivery of CPT by developing long-lasting liposomes using various weights (M.W. 2000 and 5000 Daltons) of the hydrophilic polymer polyethylene glycol (PEG). Conventional and PEGylated liposomes containing CPT were formulated via the lipid film hydration method (solvent evaporation) using a rotary flash evaporator after optimising various formulation parameters. The following physicochemical characteristics were investigated: surface morphology, particle size, encapsulation efficiency, in vitro release, and formulation stability. Different molecular weights of PEG were used to improve the encapsulation efficiency and particle size. The stealth liposomes prepared with PEG5000 were discrete in shape and with a higher encapsulation efficiency (83 ± 0.4%) and a prolonged rate of drug release (32.2% in 9 h) compared with conventional liposomes (64.8 ± 0.8% and 52.4%, respectively) and stealth liposomes containing PEG2000 (79.00 ± 0.4% and 45.3%, respectively). Furthermore, the stealth liposomes prepared with PEG5000 were highly stable at refrigeration temperature. Significant changes were observed using various pharmacokinetic parameters (mean residence time (MRT), half-life, elimination rate, volume of distribution, clearance, and area under the curve) of stealth liposomes containing PEG2000 and PEG5000 compared with conventional liposomes. The stealth liposomes prepared with PEG5000 showed promising results with a slow rate of release over a long period compared with conventional liposomes and liposomes prepared with PEG2000, with altered tissue distribution and pharmacokinetic parameters.

Outdoor Atmospheric Microplastics within the Humber Region (United Kingdom): Quantification and Chemical Characterisation of Deposited Particles Present

Atmospheric microplastics (MPs) have been consistently captured within air samples on a global scale. Locations with high human activity are reported to have high MP levels. An urban sampling site in the Humber region (U.K.) has been sampled over a 13-month period, providing a seasonal variation profile of MP levels, size, shape, and polymer types that humans are exposed to. Mean MP levels, measured using passive fallout into a container, were 3055 ± 5072 MP m−2 day−1 (1164 median). An increase in levels with a decrease in MP size was observed, consisting of mainly film-shaped MPs (67%) that were polyethylene (31%) and nylon (28%) polymer types. No relationship between rainfall and MP fallout levels was observed. In parallel, MPs within five urbanised locations relevant to human exposure were characterised over a 2-week period. An overall MP mean (and standard deviation) of 1500 ± 1279 was observed (1012 median), from which petroleum resin accounted for 32% of MP polymer type, with a higher prevalence within industrial and roadside zones. These comprised mainly fragment (52%) and film (42%) shapes, and the MPs levels increased with decreasing particle size. The results provide novel information on characterising polymer levels and types, and can inform cellular toxicity studies, investigating the consequences of human MP exposure.

Plasticulture for Vegetable Production: A Review

Plasticulture is a method of producing crops in which the use of plastic polymers provides a major advantage. Plasticulture arose from of the late 1930s research and innovation of polyethylene polymer, which was later commercialized as plastic films, mulches, as well as drip-irrigation tubes but also tape in the early 1950s. Other polymers, like as polyvinyl chloride, polypropylene, as well as polyesters, were subsequently developed and used in pipes, fittings, fertilizer application equipment, connectors, including row coverings, extending the usage of plastic elements in this industrial system even further. Plastic mulches, fertigation/chemigation, drip irrigation, fumigation, solarization, windbreaks, stand creating technology, seasonal-extending technology, pest controls, cropping methods, postharvest handling, and marketing are all part of the plasticulture system.. Plasticulture-based vegetable crops production is undeniably a labor-intensive process with high input costs and management needs.

Fatigue Analysis of a Forged Medium Carbon Low Alloy Steel Quenched in a Polymer for Vehicle Structures Applications

The fatigue properties of medium carbon low alloy forged Steels (EN 18, EN19, EN 24 and EN25) for untreated (forged) and polymer quenched samples are investigated. A dissolving temperature of 855ºC with a soaking period of 60 minutes followed by step tempering of 575ºC and 220ºC was used for the heat treatment. Thereafter quenching was performed in a polymer (polyethylene glycol 10% and 30%) separately. Fatigue tests were performed on both untreated and polymer quenched samples. The polymer quenched samples outperform the untreated samples. The fatigue analysis has been carried out using ANSYS and substantiated by the experimental results for the polymer quenched samples loaded to 30% of UTS. The heat-treated specimens had a fine-tempered martensite structure with a trace of ferrite, which enhances the toughness characteristics required for vehicles structures applications.

Atomistic molecular dynamics in polyethylene oxide and polymethyl methacrylate blends having significantly different glass transition temperatures

AbstractThe highly asymmetric polymer blends, polyethylene oxide and polymethyl methacrylate systems, having extraordinary different original glass transition temperature (Tg) values, have been examined by the fully atomistic molecular dynamics simulations. We have determined densities against temperatures after establishing the conditions of models to clarify the composition‐dependent behavior of the systems. The relations show the intermediate region in addition to the Tg1 and Tg2, the high and low‐temperature Tg values, respectively. The trend found in the polymer blends is reproduced well from the weighted sum of plots for both homopolymers by assuming the additivity of local volumes. The dynamics of the polymer blend exhibited similar behavior with ionic systems but with different time scales. These results open new understandings for the physical meanings of the Tg in polymer blends and their relation with dynamics.

Aspirin Repurposing in Folate-Decorated Nanoparticles: Another Way to Target Breast Cancer.

Breast cancer affects more than 1 million women per year worldwide. Through this study, we developed a nanoparticle-based drug delivery system to target breast cancer cells. Aspirin has been found to inhibit thromboembolic diseases with its tumor-preventing activity. As a consequence, it relieves disease symptoms and severity. Here, mesoporous silica nanoparticles (MNPs) have been used to deliver aspirin to the tumor location. MNP-based aspirin in folic acid (F)-conjugated polydopamine (MNP-Asp-PD-PG-F) vehicles are prepared for targeted breast cancer therapy. The vehicle hinges on MNP altered with polymer polyethylene glycol (PG), polydopamine (PD), and F. The delivery vehicle was studied for in vitro drug release, cytotoxicity, and breast cancer cell proliferation. F-conjugated drug delivery vehicles let MNPs achieve an elevated targeting efficacy, ideal for cancer therapy. It was also observed that compared to free aspirin, our drug delivery system (MNP-Asp-PD-PG-F) has a higher cytotoxic and antiproliferative effect on breast cancer cells. The drug delivery system can be proposed as a targeted breast cancer therapy that could be further focused on other targeted cancer therapies. Delivering aspirin by the PD-PG-F system on the tumor sites promises a therapeutic potential for breast cancer treatment.

UV Radiation Crosslinking of Acrylated Palm Olein (APO) Copolymer Resins for 3D Printing

Generally, only a few especially acrylic monomers have photoabsorption characteristics to allow for effective stereolithography (STL) to take place. Biomaterial product from palm oil, Acrylated Palm Olein (APO), is seen as an ideal alternative to petroleum-based polymers due the diminishing petrochemical supply and abundant of the natural polymer in the market. In this study, APO as a biopolymer is introduced to synthetic polymers Polyethylene Glycol Dimethylacrylate (PEGDMA) and Polyethylene Glycol Diacrylate (PEGDA), separately. All three polymers offer photoabsorption characteristics that enable them to be the resins for ultraviolet (UV) 3D printing. The crosslinking of both copolymers is optimized by comparing two different UV radiation techniques; UV cured machine and UV STL 3D printer. The degree of crosslinking for both APO-co-PEGDMA and APO-co-PEGDA through gel fraction analysis are studied and compared with their prepolymer resins. As predicted, the maximum degree of crosslinking of APO-co-PEGDMA and APO-co-PEGDA samples are achieved from the fabrication of samples by 3D printing and recorded at 67.50% and 59.50% respectively, comparing to the samples cured by UV cure machine, which recorded maximum crosslinking percentage at only 21.31%. Further analysis is done using swelling test to study water absorption capacities of copolymers and results shows that APO-co-PEGDMA able to retain water at maximum of 42.47% and APO-co-PEGDA at 52.02% from the 3D printed samples, and recorded lowest readings at 22.82% and 25.56% respectively. UV cured samples are recorded to have lowest readings at 3.89% for APO-co-PEGDMA, and 4.23% for APO-co-PEGDA. Fourier Transform Infrared (FTIR) Spectroscopy confirmed the successful crosslinked of the copolymers. Analysis of FTIR shows that there are presence of new peaks and shifting of peaks, indicating that APO is crosslinked with PEGDMA backbone as well as PEGDA backbone. These also suggest that both polymers are suitable to be incorporated with APO as new photopolymer resins, fabricated using UV radiation crosslinking, with PEGDMA shown a slightly better result. All results are agreeable with FTIR results.

Analysis of Mechanical Property Degradation of Outdoor Weather-Exposed Polymers.

It is well known that many polymers are prone to outdoor weathering degradation. Therefore, to ensure the safety and integrity of the structural parts and components made from polymers for outdoor use, their weather-affected mechanical behavior needs to be better understood. In this study, the critical mechanical property for degradation was identified and modeled into a usable format for use in the virtual analysis. To achieve this, an extensive 4-year outdoor weathering test was carried out on polycarbonate (PC), polypropylene (PP), polybutylene terephthalate (PBT), and high-density polyethylene (HDPE) polymers up to a total UV irradiation of 1020 MJ/m2 at a 315~400 nm wavelength. In addition, tensile tests were performed by collecting five specimens for each material at every 60 MJ/m2 interval. With the identification of fracture strain retention as the key performance index for mechanical property degradation, a fracture strain retention function was developed using logistic regression analysis for each polymer. In addition, a method for using fracture strain retention function to establish a mechanical property degradation dataset was proposed and successfully tested by performing weathering FE analysis on the virtual automotive collision behavior of a PC part under intermittent UV irradiation doses. This work showed the potential of using fracture strain retention function to predict the performance of polymeric components undergoing mechanical property degradation upon outdoor weathering.

Experimental research on synergistic drag reduction of cationic surfactant and nonionic polymer

The coupling of surfactant and polymer can weaken their shortcomings, improve drag reduction rate, and enhance the stability of drag reduction. This paper takes the cationic surfactant octadecyl trimethyl ammonium chloride and the nonionic polymer polyethylene oxide as the research objects, and uses the coaxial cylinder system of Anton Paar MCR102 to study the synergistic drag reduction of cationic surfactant and nonionic polymer. The experimental results show that cationic surfactants and nonionic polymers has obvious synergistic drag reduction. Compared with 800 ppm OTAC/NaSal solution or 40 ppm PEO solution, the drag reduction increases by 61.49% and 19.78%, respectively. Moreover, the drag reduction rate of the mixed solution is not monotonically increasing with the surfactant concentration. When the OTAC/NaSal concentration reaches polymer saturation point of 1200 ppm, the drag reduction rate of the mixed solution reaches the maximum value of 14.09% and the drag reduction rate increases by 34.15%; when the concentration of OTAC/NaSal is less than 1200 ppm, the drag reduction rate increases with the increase of the concentration of cationic surfactant; however, when the concentration of OTAC/NaSal is greater than 1200 ppm, the drag reduction rate is basically stable. In addition, the shear resistance of the mixed solution is significantly enhanced.

What type of plastic do sea turtles in Korean waters mainly ingest? Quantity, shape, color, size, polymer composition, and original usage

Globally, sea turtles are at high risk of ingesting plastic. However, research on plastic ingestion by sea turtles in East Asia is scant, and no quantitative or qualitative investigation has been conducted in Korean waters. This study examined the plastic ingestion of sea turtles stranded, floating, or incidentally captured in Korean waters between 2012 and 2018. The quantity, shape, color, size, polymer type, and original usage of plastic debris (>1 mm) ingested by sea turtles were analyzed after being sorted from the gastrointestinal tracts of 34 turtles (21 loggerheads (Caretta caretta), 9 green turtles (Chelonia mydas), 2 leatherbacks (Dermochelys coriacea), and 2 olive ridleys (Lepidochelys olivacea)). The ingestion frequencies of greens, loggerheads, olive ridleys, and leatherbacks were 100%, 81%, 50%, and 50%, respectively. The mean amount of plastic ingested was 108 ± 253 mg/kg (38 ± 61 n/ind.). The ingested debris tended to be films and fibers (>80%), light in color (white and transparent; 65%), and light polymers (polyethylene, polypropylene, polypropylene [poly (ethylene:propylene)], expanded polystyrene; 93%). The original uses were identified for 187 pieces; single-use plastics (e.g., plastic bag and packaging) and fishing and aquaculture items (e.g., twine and net) were found to dominate. Green turtles (264 ± 433 mg/kg) ingested significantly higher amounts of plastic than loggerheads (72.8 ± 156 mg/kg). Green turtles ingested mostly fibers (51%), such as rope, twine, and net, while loggerheads ingested largely films (61%), such as plastic bags and packaging. Interspecies differences in quantities and shapes of ingested debris may be related to their distinct feeding habits and geographical range of movement. The present study demonstrates that sea turtles foraging in Korean waters are considerably affected by marine plastic debris, and indicates that proper waste management of single-use plastics and fishing gears is urgently needed to mitigate the damage that plastic debris causes to marine wildlife.

A straightforward method for microplastic extraction from organic-rich freshwater samples

The extraction of microplastics from organic-rich freshwater samples is challenging and limited information is available in the literature. This study aims at developing efficient methods for water volume reduction and organic matter removal in freshwater samples, while focusing on the reduction of the economic and environmental costs, maintaining microplastics integrity and avoiding contamination. For the water volume reduction approach, centrifuging freshwater samples (water, sediment, algae, leaves, driftwood, fish tissue) at different speeds (3500, 6000 rpm) and times (5, 10 min) showed that 3500 rpm for 5 min was efficient to settle the mineral and organic material, while preserving the polymers and showing high microplastic recovering rates (93 ± 6%). These recovery rates were significantly higher than the traditional sieving approach (77 ± 22%). The posterior minimal consumption of reagents resulting from the reduction of water volume helped to reduce the economic and environmental costs of the devised methodology, becoming more aligned with green chemistry principles. For biogenic organic matter removal, four digestion solutions were tested on freshwater samples, namely 10% potassium hydroxide, Fenton reagent (30% H2O2 + Fe(II)), 7% and 10% sodium hypochlorite (NaClO), under 3 periods of time (1, 6 and 15 h), at 50 °C. Both 7% and 10% NaClO showed the highest rates of organic matter removal (86 ± 1% and 90 ± 1%, respectively), after 6 h at 50 °C. Exposure of virgin and aged polymers (polyethylene, polypropylene, polystyrene, polyvinyl chloride, nylon, polyethylene terephthalate) to NaClO showed no weight, visual, surface structure, Fourier transform infrared spectra and carbonyl index changes, except for nylon, although not to an extent that affected its identification. This method resulted in high recovery rates of polymers (92 ± 6%). Thus, 7% NaClO at 50 °C for 6 h (or overnight) may be efficiently used for microplastic analysis in organic-rich freshwater samples.

Evolution of the Surface Structure and Functional Properties of the Electroconducting Polymer Coatings onto Porous Films

Composite systems containing electroconducting polymer coatings (polyaniline and polypyrrole) applied to porous films of semicrystalline polymers (polyethylene, polypropylene, and polyvinylidene fluoride) have been prepared. Porous supports were obtained in the process based on polymer melt extrusion with subsequent annealing, uniaxial extensions, and thermal stabilization. Conducting coatings were formed by the oxidative polymerization of the monomers directly onto the porous supports. The structure (overall porosity, permeability, pore sizes, factor of orientation) and morphology (specific surface and character of the film surface) of the supports were characterized by sorptometry, filtration porosimetry, atomic force microscopy (AFM), and X-ray scattering techniques. It was observed that the porous supports have a strongly developed relief surface which is formed in the pore formation process. It was proven by scanning electron microscopy (SEM) that the porous supports have an oriented structure, and the surface of the composites is defined by the morphology inherent in the conducting component. It was shown that these composites (porous support/conducting coating) demonstrate electric conductivity both along the surface and between surfaces. It was demonstrated that the deposition of conducting coatings leads to an increase in the water wettability of the composites compared with pronounced hydrophobic supports. The composites are characterized by good adhesion between components due to a relief film surface as well as high mechanical strength and elasticity provided by the oriented character of the supports.

Comparative Analysis of the Effect of Fibre Architecture on the Tensile Properties of Sisal Fibre Reinforced Polyethylene Polymer Composite

This work investigates the effect of fibre architecture on the mechanical properties of composite laminates fabricated from natural sisal fibres reinforced with polyethylene polymer matrix. The main objective for this is to determine which architectural pattern produces the best material in terms of mechanical properties that can be employed for use in the fabrication of engineering components to replace the more expensive components produced from the highly expensive synthetic fibre materials. Four fibre architectural patterns were chosen and tailor-made for the study namely;±45° angled ply, 0°/90° cross ply, 90° and 0°unidirectional plies. A five layered composite laminates were manufactured from the fabrics and subjected to mechanical tensile tests using Instron universal testing machine (model 4467) having 30kN load cell attached to it and an extensometer gauge length 75mm at a crosshead speed of 200mm/min. The result of the mechanical tests revealed that the 90° laminate gives the best mechanical properties such as; elastic modulus, yield strength and tensile strength amongst the fabricated composite laminates. It was followed by the ±45° angle plied laminate, the 90° unidirectional fibre laminate and lastly the 0°unidirectional fibre laminate has the lowest mechanical properties amongst all the laminates tested. SEM micrographs of the fractured surfaces reveal that the failure modes of the laminates are characterized mostly by fibre-matrix debonding, fibre delamination, fibre splitting, fibre cracking and so on.

Microplastics contributed much less than organic matter to the burial of polycyclic aromatic hydrocarbons by sediments in the past decades: a case study from an urban lake.

The role of microplastics in burying hydrophobic organic compounds remains largely unknown. Sediment cores collected from the center of a typical urban lake (Lake Qianhu) in China were chosen to explore the contribution of microplastics to the burial of polycyclic aromatic hydrocarbons (PAHs) by sediments, and to elucidate how this contribution changed with microplastic composition and the hydrophobicity of PAHs on a decade scale. Our results showed that the concentration of individual PAHs adsorbed by microplastics varied from detection limit (LOD) to 7.2 mg g-1 MP, which was much higher than the LOD to 31.0 μg g-1 TOC buried by total organic carbon. However, the amount of individual PAHs adsorbed by microplastics only contributed to 0-34.2% of that in sediments. Changes in the composition of microplastics, including the increased proportion of polyethylene and polypropylene : polyethylene polymer in sediments, resulted in the average microplastic sediment burial ratios (MSBRs) of most PAHs increasing by 0.13% to 2.7% in the period from 1997 to 2018 compared with those in the period from 1975 to 1996. The average MSBRs varied with the hydrophobicity of PAHs, which increased with log Kow value if it varied from 3.45 to 5.20, but decreased with log Kow if it was in the range of 5.30 to 6.50. Our study provides novel knowledge on the contribution of microplastics to the burial of PAHs by sediments.

The potential emission of personal care products derived plastic microbeads: a case study of Ho Chi Minh City, Vietnam

Plastic microbeads are commonly used in many personal care products and can cause adverse impacts to the environment and ecosystem. The toxicological problem with these pollutants are due to their non-biodegradable materials, which washed down the drain; end up accumulating in the aquatic system causing increased frequency and quantity of items ingested by biota. Several polymers (e.g. Polyethylene) especially those found in plastic microbeads have been reported to be in tandem with other toxic contaminants serving as a vector for their transports in the environment. Thus, the legislative ban for plastic microbeads is used in some developed countries, but many countries including Vietnam do not take any legal action. This present study aimed at potential microbead’s existence in the cosmetic market of Ho Chi Minh City (HCMC). The list and ingredients of microbeads containing personal care products (toothpaste, facial cleanser/scrubs and body wash/scrubs) have been checked. The microbeads containing PCPs are common for all explored categories, especially in toothpaste. Data from the online questionnaire survey have shown that 98% of respondents have frequently used at least one microbead containing product. Four polymers (Polyethylene, Acrylates Copolymer Styrene/Acrylates Copolymer and Acrylates/C10-30 Alkyl Acrylate Crosspolymer) have been observed in the product package of several facial cleansers and body scrubs. Thus, the potential negative impacts of this contaminant should not be ignored.

Evaluation of tensile and flexural strength properties of virgin and recycled high-density polyethylene (HDPE) for pipe fitting application

Innovative ways of eliminating heavy plastic waste all over the world must be designed and implemented via recycling of post used plastic materials by making new products. As a result of continuous use of plastic materials, adverse effect on the environment and economic issues had been a problem confronting the post-consumer recycling of these materials. High-Density Polyethylene (HDPE) polymers are widely being used and its products are preferable than metals having the properties such as lightweight, ease of manufacture, stronger and tough.This research work focuses on investigating the flexural and tensile strength properties of virgin and recycled HDPE for pipe fitting application. The mixing of recycled with virgin HDPE were done at different weight percentages (0:100, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10, and 100:0). Eleven (11) T-reducer pipe fitting samples were produced via injection moulding machine. Data of flexural strength test for selective samples similar with tensile test in showed that 100 wt% virgin HDPE had 39.98 MPa whereas 100 wt% recycled HDPE had 20.88 MPa. Generally, all the mechanical (tensile and flexural) properties decreased as number of recycled contents increased. Because, recycled high density polyethylene scrap (rHDPE) have weaker bond strength than virgin high density polyethylene (vHDPE) materials. Bond strength is very strong in virgin HDPE, and they also have molecular weight that is large. Also, there is highest rigidity in virgin HDPE. Rigidity is very high in virgin HDPE due to high toughness. So, with lower load, bond strength is not allowed to break. But there is weaker bond strength in 100% recycled scraps of HDPE as a result of different kinds of stresses they have been subjected to during prior usage.

An experimental study on compressive properties of high density polyethylene-nano alumina-groundnut shell hybrid composites

In recent years, bio-fibers have become increasingly popular as reinforcements for thermoplastics and thermosets. Research into the use of natural fibers such flax, bamboo, sisal, hemp, and jute as reinforcing elements in the production of various composites has been considerable. Groundnut shell particles and refractory alumina powder were combined with high density polyethylene (HDPE) polymer matrix to create new bio-based composites in this study. The results were promising. Composite boards were synthesized by with HDPE with randomly distributed nano alumina and groundnut shell particles with volume percentages of 95:0:5, 95:2.5:2.5 and 95:5:0. ASTM standards were used to evaluate the compressive, shore hardness and water intake characteristics of the composites. The highest compressive load, compressive strength, increase in area, maximum displacement, displacement at break and compressive strain were analyzed for the specimen having HDPE, nano alumina and groundnut shell particles proportion 95:2.5:2.5. Using HDPE, nano alumina, and groundnut shell particles, Possibly a composite might be produced that could replace wood in many settings.

Polyethylene degradation by larvae of wax moth

Recently various reports on biodegradation of plastics by wax moths, Galleria mellonella and Achoria grisella have emerged upon and these offer an opportunity for development of technology to degrade the polyethylene polymer biologically. Galleria mellonella and Achoria grisella which are most damage causing honeybee pests were recently found causing disintegration of the plastic waste. Present review article provides the detailed description about the morphology of the insect and also provides description about plastic degradation capacity of wax moth. This also includes comprehensive informative account on microbiota dependent and microbiota independent biodegradation of polyethylene.

Features of technology of manufacture of power high voltage cables with thermoplastic polymeric insulation

The problem of high-voltage power cables is associated with complex technological processes in their manufacture. One of the main processes in the manufacture of cables is extrusion. There is a huge number of parameters (known as process parameters) at the stage of extrusion process that directly affect the performance of isolation and cable as a whole. It is shown that the important parameters of the process of extrusion are the melt temperature, speed, pressure, screw speed, the type of matrix used and the cooling medium in the extruder. The temperature and pressure of the melt are among the largest important parameters in the process of extrusion that determine the productivity of the process. The influence of temperature, pressure and fluctuations of these parameters on a complex of mechanical and electrical characteristics of the cable are analyzed. It is substantiated that the rheological properties of polymers are prone to oscillations, which causes problems in the production of cables. The complexity and large number of process parameters involved in the production of cables are complicated by the process of control, which determines the appearance of defects in the form of cracks, air cavities and porosity in high-voltage isolation. It is argued that the use of power cables with a cross-linked polyethylene, which is a thermosetting insulating material, causes the complexity of processing both in the manufacturing stage and in operation. Development of technology for the introduction of thermoplastic isolation provides secondary processing to implement projects of power-high-voltage variable and direct current cables. A comparative analysis of electrical, mechanical and thermal parameters of cross-linked polyethylene and thermoplastic polymers as an alternative of thermosetting isolation is presented. The article presents the features of the technological regime of extrusion of polymer isolation based on thermoelastoplasts, in particular, polypropylene compositions, which are due to the lower values of the coefficient of thermal conductivity of such compositions in comparison with polyethylene. Models are presented to describe the process of extrusion of thermoplastic isolation of power cables, taking into account the flow of molten polymeric material as a non-Newtonian, uncompressive, isothermal fluid. The necessity of determining the values of the coefficients of thermal conductivity and heat capacity of polypropylene compositions in a wide temperature range to reduce the likelihood of technological defects in high-voltage thermoplastic isolation is substantiated.